Abstract: In a vehicle production process, a system for detecting selected surface defects of a vehicle body prior to painting generally consisting of a conveyor operative for advancing a plurality of such vehicle bodies along a line of travel; an array of devices disposed transversely of the line of travel, operative to irradiate at the selected angles, sequential transverse sections of each of such vehicle bodies with grid patterns of light; a plurality of devices, operative to optically detect reflective grid patterns of light from the transverse sections; a computer including a processor and a database provided with files of reference data representing relevant defect surfaces of selected vehicle bodies, operative to process data generated by the detecting devices, utilizing triangulation techniques and accounting for three-dimensional phase shifts, to generate composite detected data, comparing such composite detected data with selected reference data to generate identification data representing coordinates of rel